1. Field of the Disclosure
The present disclosure relates to a semiconductor device in which a passivation film is formed on or over a semiconductor substrate and a method of manufacturing the semiconductor device.
2. Description of the Related Art
Semiconductor devices including a semiconductor substrate, a semiconductor element formed in or on the semiconductor substrate, and a passivation film that protects the semiconductor element are generally known (see, for example, Japanese Unexamined Patent Application Publication No. 7-130731). Japanese Unexamined Patent Application Publication No. 7-130731 describes a structure in which a passivation film is formed by alternately stacking two types of compressive stress films having different densities.
A passivation film is a protective film formed on or over a surface of a device, and the passivation film is formed in the final step of a wafer process. Therefore, on a wafer surface on which a passivation film is to be formed, for example, a semiconductor layer, an insulation layer, an organic layer, and a metal layer have been formed. That is, the wafer surface has the process history accumulated before the passivation film is formed. The wafer tends to have residual compressive stress due to the differences in the thermal expansion coefficient between various materials.
In the passivation film described in Japanese Unexamined Patent Application Publication No. 7-130731, a compressive stress film having high density is disposed in the lowest layer. In general, a compressive stress film having high density tends to have compressive stress larger than that of a compressive stress film having low density. The compressive stress due to the compressive stress film having high density is added to the residual compressive stress of the wafer. As a result, a problem arises in that the wafer may warp and the passivation film may crack due to these compressive stresses.